1. Field of the Invention
The present invention relates to a device for preventing fluid free flow in a fluid administration system, and more particularly to an anti-free flow valve device disposed within a lumen of a tube assembly. More specifically, the present invention relates to a tube diameter dependent anti-free-flow valve device that prevents fluid free flow when the tube assembly is in a relaxed condition, while permitting uninhibited fluid flow when the tube assembly is in a stretched condition.
2. Prior Art
Administering fluid containing medicine or nutrition to a patient is generally well-known in the art. Typically, fluid is supplied to a patient by a tube assembly which provides a fluid pathway between a fluid source and a patient. The fluid is supplied to the patient through the tube assembly by either an enteral connection which accesses a visceral organ (gastrointestinal feeding) of a patient or through a parenteral connection which accesses a non-visceral organ (intravenous feeding).
Fluid flow rate through the tube assembly may be manually controlled by a mechanical clip which is designed to progressively occlude the tube assembly and selectively impede fluid flow induced by the force of gravity. One such mechanical clip which operates to occlude a portion of the tube assembly is a conventional roller clamp that has a hollow body with opposed outlets and a pair of angled slots formed opposite of one another transverse to the outlets. The clip further includes a wheel having an axle which is coupled to the body through the slots. A portion of the tube assembly is then inserted through both the outlets and the wheel axially advanced along the slots to pinch a portion of the tube against the body which progressively occludes the tube assembly. Although the mechanical clip operates to provide a cost-efficient method for controlling fluid flow rate, the clip must be manually actuated by the user. Further, the wheel of the mechanical clip can be inadvertently bumped or jostled out of position resulting in an inappropriate flow rate.
In order to better enhance fluid flow rate control in a fluid administration system, calibrated pumps have been utilized. One such calibrated pump is a peristaltic pump connected in-line along a portion of the tube assembly between the fluid source and the patient. The peristaltic pump advances the fluid through the tube assembly by progressively occluding successive portions of the tube assembly and urging each occluded portion forward. When a peristaltic pump is utilized to control the fluid flow rate, mechanical clips are typically not employed or are disengaged to prevent the clip from interfering with the operation of the pump.
Although peristaltic pumps have substantially advanced the art, further improvements are required. For example, once the tube assembly is disengaged from the pump fluid flow rate through the tube assembly becomes unrestrained as fluid is drawn through the tube assembly due to the force of gravity. This situation is known as fluid free flow and may present an undesirable, or even life-threatening situation, if left undetected because of the risk of overfeeding or overmedicating a patient.
In order to overcome the above-noted drawbacks to fluid administration systems utilizing pumps, several devices have been suggested which operate to automatically occlude a portion of the tube assembly and prevent fluid free flow when the tube assembly becomes disengaged from the pump while also permitting uninhibited fluid flow when the tube assembly is properly engaged to the pump. For instance, a variety of automatic occluders have been suggested to improve the art such as those disclosed in U.S. Pat. No. 4,689,043 to Bisha entitled xe2x80x9cIV Tube Activatorxe2x80x9d which describes a clamp for use with a peristaltic pump. The clamp includes a V-shaped channel which is spring biased into a closed position where the narrow portion of the V-shaped channel is sized to substantially crimp, or occlude, a portion of the tube assembly and prevent fluid free flow therethrough. The clamp is placed in an open position by a handle which overlays the pump and depresses the springs such that the tube assembly is positioned within the wider portion of the V-shaped channel to permit unrestricted flow through the tube assembly when the pump is operating. When the handle is released, the V-shaped portion will automatically slide into the closed position and prevent fluid free flow by occluding a portion of the tube assembly.
Another automatic occluder is disclosed in U.S. Pat. No. 5,704,582 to Winterer, et al. entitled xe2x80x9cPinched Clipped Occluder for Infusion Setsxe2x80x9d which describes a clip that is positioned between a housing and a cover of a pump. The clip has a plunger biased by a spring towards a portion of the tube assembly so that the lumen of the tube assembly becomes occluded by the plunger. Fluid flow through the tube assembly may only be established when the plunger is biased away from the lumen of the tube assembly which occurs when the cover is properly coupled with the housing. However, once the cover becomes disengaged from the housing, the plunger is automatically biased into the closed position by the spring to prevent fluid free flow.
Although both of the aforementioned automatic occluders have advanced the art, both devices are mechanically complex and prone to mechanical failure. In addition, the mechanical complexity of these devices also results in occluders which are expensive to manufacture. Accordingly, there is a need in the art for a simple valve device that is capable of preventing fluid free flow when the tube assembly is disengaged from the pump, while permitting uninhibited fluid free flow when the tube assembly is disengaged from the pump.
In brief summary, the present invention overcomes and substantially alleviates the deficiencies present in the art by providing a valve device for preventing fluid free-flow in a fluid administration system. The valve device of the present invention is disposed within the lumen of a tube assembly for preventing fluid free flow when the tube assembly is disengaged from the pump, while permitting uninhibited fluid flow when the tube assembly is engaged with the pump.
Preferably, the pump of the fluid administration system used in conjunction with the present invention includes a rotor for advancing fluid through the tube assembly and a pair of recesses positioned adjacent the rotor for retaining portions of the tube assembly to the housing of the pump during operation of the system. The tube assembly comprises three interconnected tube segments each having a distal and proximal ends for providing a fluid pathway between the fluid source and a patient. The fluid source is connected to the distal end of the first tube segment, while the proximal end thereof is connected to the distal end of the second tube segment by a drip chamber having an abutment surface. The proximal end of the second tube segment is interconnected to the distal end of the third tube segment by a coupling having an external flange. Finally, the proximal end of the third tube segment is attached to a patient through either an enteral or parenteral connection.
The tube assembly is engaged with the pump by threading a portion of the assembly around the rotor with the abutment surface of the drip chamber and external flange of the coupling engaged within the first and second recesses, respectively, of the pump. Preferably, the second tube segment as it is engaged around the rotor has a length which permits the abutment surface and the external flange to be properly captured by the first and second recesses and place the second tube segment in a stretched condition. Each of the tube segments has a lumen formed therethrough to allow the passage of fluid through the tube assembly. Alternatively, the valve device may be used with a tube assembly not having a drip chamber or coupling.
Preferably, the valve device of the present invention is disposed within the lumen of one of the tube segments to prevent fluid free-flow when the tube assembly is disengaged from the pump. The valve device comprises a body having a generally cylindrical portion formed adjacent a tapered portion. The cylindrical portion of the valve device includes an outlet and both the cylindrical portion and the outlet are generally circular in configuration. The tapered portion includes opposite beveled surfaces having ends with the beveled surfaces being bounded by a pair of side walls. Preferably, the beveled surfaces are planar in shape, while the side walls have a generally rounded configuration. The tapered portion also includes a slit formed between the ends of the beveled surfaces and a passage which interconnects the outlet and the slit of the valve device such that any fluid that enters through the slit can pass along the passage and exit from the outlet. Preferably, the valve device is disposed within the lumen of the second tube segment adjacent the coupling with the slit or proximal end of the valve device facing the proximal end of the second tube segment and the outlet directed towards the distal end thereof. The cylindrical portion of the valve device is sized and shaped to sealingly engage against the inner circumference of the lumen and prevent fluid flow around the valve device at all times.
When the second tube segment is in a relaxed condition or disengaged from the pump, the slit is placed in the closed position by the ends of the beveled surfaces confronting one another and occluding the lumen of the second tube segment. However, once a tensile force is applied along the second tube segment by stretching it, the second tube segment assumes a stretched condition which urges the ends of the beveled surfaces away from one another as the inner diameter of the lumen is decreased and elongates the body of the valve device. This action places the slit in the open position, thereby allowing fluid to pass through the lumen of the second tube segment. Once the applied tensile force is released by disengaging the tube assembly from the rotor, the inner diameter of the lumen increases and the body of the valve device returns to the relaxed condition. The expansion of the lumen when the tube assembly is in the relaxed condition permits the ends of the beveled surfaces to come together again and return the slit to the closed position. Alternatively, the slit may be placed in the open position by manually pinching the body of the valve device transverse to the slit which also causes the ends of the beveled surfaces to be urged away from one another as the inner diameter of the lumen is decreased.
In operation, the valve device of the present invention prevents fluid free flow whenever the tube assembly is disengaged from the pump while permitting uninhibited fluid flow when the tube assembly is engaged around the rotor of the pump, or the valve device is manually actuated by the user. The valve device is placed within the lumen of the tube assembly during manufacture. To utilize the valve device, the user first connects the first tube segment of the tube assembly with the fluid source and allows fluid to flow to the point where the valve device is located within the tube assembly. The user then primes the tube assembly in order to evacuate air from the remaining portions of the tube assembly and initiate fluid flow therethrough. Preferably, the tube assembly may be manually primed by stretching a portion of the tube assembly surrounding the valve device which urges the ends of the beveled surfaces away from one another as the body of the valve device elongates and opens the slit to fluid flow through the lumen of the tube assembly. Air is then forced out through the remaining portions of the tube assembly.
To regulate and urge the fluid through the tube assembly, the tube assembly is connected to the pump. Specifically, the abutment surface of drip chamber is engaged within the first recess of the pump and the second tube segment is stretched around the rotor. The external flange is then inserted into the second recess of the pump to retain the second tube segment in a stretched condition. Due to the tensile force applied to the second tube segment, the inner diameter of the lumen is decreased such that the lumen confronts and urges the pair of side walls together which urges the ends of the beveled surfaces away from one another to place the slit in the open position. Once in the open position, fluid flow is established through the lumen of the second tube segment. However, if the tube assembly becomes disengaged from the pump, the tensile force exerted upon the second tube segment will be released which automatically results in expansion of the inner diameter of the lumen so that the ends of the beveled surfaces confront one another and close the slit to fluid flow.
Accordingly, the primary object of the present invention is to provide a valve device which prevents fluid free-flow.
Another object of the present invention is to provide a valve device that prevents fluid free flow when the tube assembly is disengaged from the pump, while permitting uninhibited flow when the tube assembly is engaged to the pump.
Still another object of the present invention is to provide a valve device which may be automatically or manually actuated.
Yet another object of the present invention is to provide a valve device that is disposed within the lumen of the tube assembly.
A further object of the present invention is to provide a valve device which reduces manufacturing costs.
These and other objects of the present invention are realized in the preferred embodiment of the present invention, described by way of example and not by way of limitation, which provides for a valve device for use in a fluid administration system to prevent fluid free-flow.
Additional objects, advantages and novel features of the invention will be set forth in the description which follows, and will become apparent to those skilled in the art upon examination of the following more detailed description and drawings in which like elements of the invention are similarly numbered throughout.